Re: [PATCH] fix scsi cmnd retries in error handling

[Hillf Danton <dhillf@gmail.com>]

On Mon, Nov 1, 2010 at 9:38 PM, James Bottomley <James.Bottomley@suse.de> wrote:
> On Mon, 2010-11-01 at 21:02 +0800, Hillf Danton wrote:
>> There are two instances of increment and test of retries of scsi cmnd
>> in functions scsi_decide_disposition() and scsi_eh_flush_done_q()
>> respectively.
>
> This analysis is incomplete.  Those two functions are called in

Though incomplete, there is chance they could be threaded up by
scsi_unjam_host(). //Hillf

> completely separate paths, so you can't remove the increment from one
> and expect the other to compensate.
>
> James
>
>> One of the increments is overwork when the corresponding cmnds are same.
>> The overwork is fixed in scsi_decide_disposition().
>>
>> Signed-off-by: Hillf Danton <dhillf@gmail.com>
>> ---
>>
>> --- a/drivers/scsi/scsi_error.c       2010-09-13 07:07:38.000000000 +0800
>> +++ b/drivers/scsi/scsi_error.c       2010-11-01 20:39:38.000000000 +0800
>> @@ -1541,7 +1541,7 @@ int scsi_decide_disposition(struct scsi_
>>        * the request was not marked fast fail.  Note that above,
>>        * even if the request is marked fast fail, we still requeue
>>        * for queue congestion conditions (QUEUE_FULL or BUSY) */
>> -     if ((++scmd->retries) <= scmd->allowed
>> +     if (scmd->retries < scmd->allowed
>>           && !scsi_noretry_cmd(scmd)) {
>>               return NEEDS_RETRY;
>>       } else {
>> --
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>
>
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